bio 1202 ch32 - animal diversity

coelom

A body cavity lined by tissue derived only from mesoderm

deuterostome development

In animals, a developmental mode distinguished by the development of the anus from the blastopore; often also characterized by radial cleavage and by the body cavity forming as outpockets of mesodermal tissue

vertebrate

A chordate animal with vertebrae, the series of bones that make up the backbone

radial cleavage

A type of embryonic development in deuterostomes in which the planes of cell division that transform the zygote into a ball of cells are either parallel or perpendicular to the vertical axis of the embryo, thereby aligning tiers of cells one above the other

diploblastic

Having two germ layers

anterior

Pertaining to the front, or head, of a bilaterally symmetrical animal

posterior

Pertaining to the rear, or tail end, of a bilaterally symmetrical animal

radial symmetry

Symmetry in which the body is shaped like a pie or barrel (lacking a left side and a right side) and can be divided into mirror-imaged halves by any plane through its central axis

dorsal

Pertaining to the top of an animal with radial or bilateral symmetry

lophophore

In some lophotrochozoan animals, including brachiopods, a crown of ciliated tentacles that surround the mouth and function in feeding

ediacaranbiota

An early group of macroscopic, soft-bodied, multicellular eukaryotes known from fossils that range in age from 635 million to 535 million years old

acoelomate

A solid-bodied animal lacking a cavity between the gut and outer body wall

tissue

An integrated group of cells with a common structure, function, or both

lophotrochozoa

One of the three main lineages of bilaterian animals; these include organisms that have lophophores or trochophore larvae

determinate cleavage

A type of embryonic development in protostomes that rigidly casts the developmental fate of each embryonic cell very early

blastula

A hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals

trochophorelarva

Distinctive larval stage observed in some lophotrochozoan animals, including some annelids and molluscs

ventral

Pertaining to the underside, or bottom, of an animal with radial or bilateral symmetry

pseudocoelomate

An animal whose body cavity is lined by tissue derived from mesoderm and endoderm

bodyplan

In multicellular eukaryotes, a set of morphological and developmental traits that are integrated into a functional whole—the living organism

blastophore

In a gastrula, the opening of the archenteron that typically develops into the anus in deuterostomes and the mouth in protostomes

bilateran

A member of a clade of animals with bilateral symmetry and three germ layers

cambrian explosion

A relatively brief time in geologic history when many present-day phyla of animals first appeared in the fossil record. This burst of evolutionary change occurred about 535-525 million years ago and saw the emergence of the first large, hardbodied animals

bilateral symmetry

Body symmetry in which a central longitudinal plane divides the body into two equal but opposite halves

larva

A free-living, sexually immature form in some animal life cycles that may differ from the adult animal in morphology, nutrition, and habitat

cleavage

The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane; or the succession of rapid cell divisions without significant growth during early embryonic development that

converts the zygote to a ball of cells

coelomate

An animal that possesses a true coelom (a body cavity lined by tissue completely derived from mesoderm)

triploblastic

Possessing three germ layers; the endoderm, mesoderm, and ectoderm. All bilateral animals are this

archenteron

The endodermlined cavity, formed during gastrulation, that develops into the digestive tract of an animal

deuterostoma

One of the three main lineages of bilaterian animals

indeterminate cleavage

A type of embryonic development in deuterostomes in which each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo

gastrula

An embryonic stage in animal development encompassing the formation of three layers; ectoderm, mesoderm, and endoderm

protostome development

In animals, a developmental mode distinguished by the development of the mouth from the blastopore; often also characterized by spiral cleavage and by the body cavity forming when solid masses of mesoderm split

body cavity

A fluid- or air-filled space between the digestive tract and the body wall

spiral cleavage

A type of embryonic development in protostomes in which the planes of cell division that transform the zygote into a ball of cells are diagonal to the vertical axis of the embryo. As a result, the cells of each tier sit in the grooves between cells of adjacent tiers

ectoderm

The outermost of the three primary germ layers in animal embryos; gives rise to the outer covering and, in some phyla, the nervous system, inner ear, and lens of the eye

mesoderm

The middle primary germ layer in a triploblastic animal embryo; develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system in species that have these structures

endoderm

The innermost of the three primary germ layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract in species that have these structures

gastrulation

In animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inward, producing a three-layered embryo, the gastrula

eumetazoan

A member of a clade of animals with true tissues. All animals except sponges and a few other groups are this

invertebrate

An animal without a backbone , they make up 95% of animal species

metamorphosis

A developmental transformation that turns an animal larva into either an adult or an adult-like stage that is not yet sexually mature